The present invention is directed to a turning bar arrangement and to a method for redirecting a web of material. The turning bar arrangement includes a turning bar and a register roller and these are useable to redirect the web of material.
Webs of material, in particular paper webs, whose width is a multiple of the widths of the finished printed products, are generally printed in rotary printing presses. In order to produce a finished printed product from the printed web, it is necessary to cut this web into a plurality of partial webs, which plurality of partial webs are initially conducted next to each other but must eventually be placed on top of each other in order to be further processed into the finished printed product, mainly by folding the plurality of partial webs in the longitudinal and transverse directions and by transverse cutting. In the course of the transverse cutting of the partial webs of material, which have been placed on top of each other, it is important that printed pages on the individual partial webs of material are exactly aligned in phase with each other, so that all of the partial webs of material are cut at the borders of respectively two sides during transverse cutting. Register rollers, which are adjustable, are employed for this purpose. The adjustability of these register rollers makes it possible to set the length of each path of the web of material by use of the turning bar arrangement in such a way that sides which are intended to be processed into a signature, on the various webs come to rest exactly on top of each other.
An example of such a turning bar arrangement is known from U.S. Pat. No. 3,734,487. This turning bar arrangement comprises a first turning bar which can be displaced transversely in relation to the feed direction of the web of material to be redirected, as well as two register rollers and one additional register roller. The register roller can be displaced in a plane located underneath the turning bars. If it is intended to place a large number of webs of material on top of each other, a stack of four turning bar arrangements, placed on top of each other, is employed. However, a relatively small number of webs of material, which are to be placed on top of each other, is sufficient for the stack of these known turning bar arrangements to become higher than a man, which height considerably complicates the maintenance of the stack of turning bar arrangements and the draw-in of the webs of material in case of a change in orders.
An arrangement for offsetting narrow paper webs in the form of partial paper webs is known from DE 38 16 900 A1.
DE-AS 17 61 899 discloses turning bars offset in height.
U.S. Pat. No. 3,734,487 shows two turning bars arranged in the shape of a triangle. A web of material can be conducted onto a register roller from these two turning bars.
EP 0 784 590 B1 shows a turning arrangement wherein a guide roller and the turning bars have different diameters. The turning bars, which are arranged at 90xc2x0 in respect to each other, have the same diameter.
The object of the present invention is directed to providing a turning bar arrangement and to providing a method for redirecting a web of material.
In accordance with the present invention, this object is attained by providing a turning bar arrangement that includes at least a first turning bar and a register roller. The web passes between the register roller and the turning bar in a plane. The first turning bar and the register roller, when viewed in a direction that is perpendicular to that plane, do not overlap. Both the turning bar and the register roller are supported at only one end. The register roller may be arranged exteriorly of the lateral frames of the printing device and its axis may be parallel to the direction of web travel in the printing machine. A second turning bar and a deflection roller may also be part of the turning bar arrangement.
The advantages which can be achieved by the present invention reside, in particular, in that it is possible to keep the structural height of the turning bar arrangement low, so that the number of turning bar arrangements which can be mounted on top of each other within a predetermined structural height is increased. Thus the number of webs of material which can be placed on top of each other in a stack of turning bar arrangements can be increased without the stack reaching to a height which would make it difficult for an operator to reach the individual turning bars of the stack for maintaining them or for drawing-in a web of material.
A section of the web extending between the first turning bar and the register roller defines a first plane which, in customary turning bar arrangements, is substantially horizontal. Since, viewed in a direction which is perpendicular to this first plane, the turning bar and the register roller do not overlap, they can be arranged to be overlapping, when viewed in a direction parallel to this plane, so that the structural height can be reduced.
A particularly effective use of the available structural volume results when the first turning bar and the register roller are arranged on the same side of this first plane.
If the register roller has a larger diameter than the first turning or direction-changing bar, the web of material conducted around the turning or direction-changing bar and the register roller can be drawn off crossing the turning or direction-changing bar without additional direction-changing elements being required for this.
A second turning bar is required for a turning bar arrangement whose delivery direction is parallel with the feed direction of the web, and the web of material can usefully be looped in sequence around the first turning bar, the register roller and the second turning bar.
If at least one of the two turning bars can be changed from an orientation wherein it is parallel in respect to another turning bar, into an orthogonal orientation, this permits the selective operation of the turning bar arrangement in parallel, or in non-parallel feed and delivery directions.
A rapid and exact change of the orientation of the changeable turning bar can be achieved if the turning bar can be rotated about an axis which intersects the turning bar at a distance from one of its longitudinal ends, and if a marking is applied on this linear end, which marking can be made to coincide in the parallel or orthogonal orientation with respectively one of two complementary markings on a support of the turning bar. Thus, when changing the turning bar over, it is sufficient to check the coincidence of the markings in order to be assured that the angles of the turning bars are set exactly.
The exact setting of the turning bar is additionally simplified if the markings have a three-dimensional shape and can be brought into interlocking contact. With a construction of this type, the engagement of the markings already assures an exact orientation of the turning bar, without it being necessary for an operator to elaborately check the orientation.